On Jul 30, 2008, at 12:05 PM, Uzelac, Adam wrote:
I believe that the problem statement (and associated use cases) that
John presented in the WG session are valid. I think it was
unfortunate that those use cases couldn't be discussed more in the
WG session. This email appears to me simply John trying to further
the discussions to bring out arguments.
One particular note I would like to share - given a comment at the
mic regarding 4474 working as designed and desired - is that there
are situations (good, bad or indifferent) that necessitate changes
in the SDP. John cited media steering as a use case. Another use
case is media steering for transcoding. Use case below:
Ent A--->SSP1--->Ent B
In this use case, Ent A and SSP1 have established certain "rules of
engagement", like G729, 2833, t.38, etc. Ent B and SSP1 have
established their own "rules of engagement", for instance G711 for
voice, inband DTMF/FAX, etc. Being there's no common denominator
for the media, the SDP in INVITE "steers" to a device that can
trancode.
This is more that sterring; the media is being terminated at a device
that transcodes it. Then a new media stream flows out the other side.
When media transcoding is occurring, media integrity is hop-by-hop. I
maintain that we have no need for an end-to-end identity
representation when the media itself is hop by hop.
Another use case, would be for those SSPs that have Lawful Intercept
requirements. Steering the media to something that will can
intercept should that be a regulatory obligation.
Same as above. Although one should note that proper use of DTLS-SRTP
to detect the lawful intercept.
--
Dean
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